File size: 5,503 Bytes
158b61b |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 |
#include "HyperPathLoader.h"
#include "TreeFragmentTokenizer.h"
namespace Moses
{
namespace Syntax
{
namespace F2S
{
void HyperPathLoader::Load(const StringPiece &s, HyperPath &path)
{
path.nodeSeqs.clear();
// Tokenize the string and store the tokens in m_tokenSeq.
m_tokenSeq.clear();
for (TreeFragmentTokenizer p(s); p != TreeFragmentTokenizer(); ++p) {
m_tokenSeq.push_back(*p);
}
// Determine the height of the tree fragment.
int height = DetermineHeight();
// Ensure path contains the correct number of elements.
path.nodeSeqs.resize(height+1);
// Generate the fragment's NodeTuple sequence and store it in m_nodeTupleSeq.
GenerateNodeTupleSeq(height);
// Fill the HyperPath.
for (int depth = 0; depth <= height; ++depth) {
int prevParent = -1;
// TODO Generate one node tuple sequence for each depth instead of one
// TODO sequence that contains node tuples at every depth
for (std::vector<NodeTuple>::const_iterator p = m_nodeTupleSeq.begin();
p != m_nodeTupleSeq.end(); ++p) {
const NodeTuple &tuple = *p;
if (tuple.depth != depth) {
continue;
}
if (prevParent != -1 && tuple.parent != prevParent) {
path.nodeSeqs[depth].push_back(HyperPath::kComma);
}
path.nodeSeqs[depth].push_back(tuple.symbol);
prevParent = tuple.parent;
}
}
}
int HyperPathLoader::DetermineHeight() const
{
int height = 0;
int maxHeight = 0;
std::size_t numTokens = m_tokenSeq.size();
for (std::size_t i = 0; i < numTokens; ++i) {
if (m_tokenSeq[i].type == TreeFragmentToken_LSB) {
assert(i+2 < numTokens);
// Does this bracket indicate the start of a subtree or the start of
// a non-terminal leaf?
if (m_tokenSeq[i+2].type != TreeFragmentToken_RSB) { // It's a subtree.
maxHeight = std::max(++height, maxHeight);
} else { // It's a non-terminal leaf: jump to its end.
i += 2;
}
} else if (m_tokenSeq[i].type == TreeFragmentToken_RSB) {
--height;
}
}
return maxHeight;
}
void HyperPathLoader::GenerateNodeTupleSeq(int height)
{
m_nodeTupleSeq.clear();
// Initialize the stack of parent indices.
assert(m_parentStack.empty());
m_parentStack.push(-1);
// Initialize a temporary tuple that tracks the state as we iterate over
// the tree fragment tokens.
NodeTuple tuple;
tuple.index = -1;
tuple.parent = -1;
tuple.depth = -1;
tuple.symbol = HyperPath::kEpsilon;
// Iterate over the tree fragment tokens.
std::size_t numTokens = m_tokenSeq.size();
for (std::size_t i = 0; i < numTokens; ++i) {
if (m_tokenSeq[i].type == TreeFragmentToken_LSB) {
assert(i+2 < numTokens);
// Does this bracket indicate the start of a subtree or the start of
// a non-terminal leaf?
if (m_tokenSeq[i+2].type != TreeFragmentToken_RSB) { // It's a subtree.
++tuple.index;
tuple.parent = m_parentStack.top();
m_parentStack.push(tuple.index);
++tuple.depth;
tuple.symbol = AddNonTerminalFactor(m_tokenSeq[++i].value)->GetId();
m_nodeTupleSeq.push_back(tuple);
} else { // It's a non-terminal leaf.
++tuple.index;
tuple.parent = m_parentStack.top();
++tuple.depth;
tuple.symbol = AddNonTerminalFactor(m_tokenSeq[++i].value)->GetId();
m_nodeTupleSeq.push_back(tuple);
// Add virtual nodes if required.
if (tuple.depth < height) {
int origDepth = tuple.depth;
m_parentStack.push(tuple.index);
for (int depth = origDepth+1; depth <= height; ++depth) {
++tuple.index;
tuple.parent = m_parentStack.top();
m_parentStack.push(tuple.index);
tuple.depth = depth;
tuple.symbol = HyperPath::kEpsilon;
m_nodeTupleSeq.push_back(tuple);
}
for (int depth = origDepth; depth <= height; ++depth) {
m_parentStack.pop();
}
tuple.depth = origDepth;
}
--tuple.depth;
// Skip over the closing bracket.
++i;
}
} else if (m_tokenSeq[i].type == TreeFragmentToken_WORD) {
// Token i is a word that doesn't follow a bracket. This must be a
// terminal since all non-terminals are either non-leaves (which follow
// an opening bracket) or are enclosed in brackets.
++tuple.index;
tuple.parent = m_parentStack.top();
++tuple.depth;
tuple.symbol = AddTerminalFactor(m_tokenSeq[i].value)->GetId();
m_nodeTupleSeq.push_back(tuple);
// Add virtual nodes if required.
if (m_tokenSeq[i+1].type == TreeFragmentToken_RSB &&
tuple.depth < height) {
int origDepth = tuple.depth;
m_parentStack.push(tuple.index);
for (int depth = origDepth+1; depth <= height; ++depth) {
++tuple.index;
tuple.parent = m_parentStack.top();
m_parentStack.push(tuple.index);
tuple.depth = depth;
tuple.symbol = HyperPath::kEpsilon;
m_nodeTupleSeq.push_back(tuple);
}
for (int depth = origDepth; depth <= height; ++depth) {
m_parentStack.pop();
}
tuple.depth = origDepth;
}
--tuple.depth;
} else if (m_tokenSeq[i].type == TreeFragmentToken_RSB) {
m_parentStack.pop();
--tuple.depth;
}
}
// Remove the -1 parent index.
m_parentStack.pop();
}
} // namespace F2S
} // namespace Syntax
} // namespace Moses
|